Sony developing back-illuminated sensor

Take everything you know about digital camera sensors and turn it around. That’s what Sony is doing in developing a new 5 megapixel CMOS imager.

The back-illuminated sensor from the company known more in digicam circles for their CCD development reverses the traditional design, gathering light from the back side of its silicon substrate rather than the front side. In doing so, Sony is claiming the new sensor will have double the light-gathering ability – that is, the sensitivity – compared to current sensor technology while maintaining low noise levels.

Back-side sensor illumination is nothing new (OmniVision recently unveiled an 8 megapixel sensor using similar technology), but it presents some design challenges. As Sony states in their own press release:

“…compared to conventional front-illuminated structures, back-illuminated structures commonly causes problems such as noise, dark current, defective pixels and color mixture that lead to image degradation and also cause a decrease in the signal-to-noise ratio.”

Changes to the photo diode and on-chip lens structures aim to overcome these issues, however, providing an ultra-sensitive sensor that produces clean images.

According to Sony, the new technology (which also allows for 60 fps video capture rates) should see applications in both the company’s camcorders and its digital still cameras.